Method for production of cellulosic materials from waste cellulose products



Psiem ed th 12, 1936 i "METHOD LOSIC LULO SE PRODUCTS FOR 1 PRODUCTION.oF oEi.I;U-j MATERIALS FROM WASTE oan- Wyly M. Billing, flopewelll va'.assignor to Her cules Powder Comp-any, Wilmington, corporation ofDelaware -Del., a: r

4 NoDrawing. Application June 13, 1934, Serial No. 130,463 g I s e 16Claims. (c1.'260 -1o) This inventionrelates to a method for theproduction of jcellulosic materials, as for example, regeneratedcellulose: cellulose esters, as, cellulose nitrate; cellulose. acetate,etc.; cellulose ethers, as benzyl cellulose, ethyl cellulose, etc., fromwaste cellulose products; and more particularly from reclaimed, mattressstuffing.

Raw cotton fibres and certain grasses and wood pulps are the presentsources ofcellulose for the production of regenerated cellulose,cellulose esters and ethers. These materials, are subjected to apurification process'which effects a removal of the unwantedconstituents-andleaves a productwhich is essentially purealpha-cellulose.

While waste cellulose products, such asreclaimed mattress stufling,afford a, cheap source of cellulose, it has hitherto been consideredimpossible to purify these waste products so that they maybe used in thepreparation of regenerated cellulose or cellulose derivativesofrequlsitelpurity. 1

,Mattre'ss stufi'ing reclaimed from old mattresses comprises a varietyof cotton fibres in admixture with suchimpurities as, for example,excelsior, wood shavings, rags, feathers, jute, hemp,

straw, cotton stalks, cotton bolls, etc; The cotton present is of a verylowgrade, since the better grades are used in textiles. 3 Mechanicalseparation of the cotton present in such a heterogenousmass is quiteobviously impracticable. Chemical purification of the reclaimedmattressstock to alpha-cellulose is likewise impracticable, sincechemical treatment strong enough to" dissolve out and'remo've' the moreresistant impuritiesipresent will so damage the cotton fibres that apurified product suitable foruse' in the production oiregeneratedcellulose orof cellulose esters orethers can only be obtained in veryuneconomical yields. "From the viewpoint of chemical composition theimpurities present in reclaimed mattress stufling can be classifiedjinto two groups. One group comprising theoils, fatsywaxes, lignins,pectins, gums, proteins, etc. is solubilized by dilute alkali ata steampressure of'from 25 to 100 lbs/sq. in. and can accordingly be removed bythe caustic or alkali cook customarily used in the purification of rawcotton' fibres to alpha-cellulose. The second group, however, comprisingthe q unpulped lignocellulosesand adipocelluloses contained, for.example'in the cotton stalks, leaves, stems and bolls, cannot "besolubilized and removed by the treatment referred tofabove,or by anytreatment not deleterious to the cotton fibres.

It has been found, however, in accordance with tially purealpha-cellulose made linters are processed.

this invention that these unremovable impurities referred to above canbe permitted to remain in the partially purified cellulosic materialobtained from reclaimed mattress stuffing duringfthe conversion of thismaterial intothe desired'cellulosic 5 material, such as r'egeneratedcellulose, cellulose esters, cellulose ethersj etc; without having" anyharmful efiect'in the necessary reactions for such conversions. Theseimpurities are not only without harmful'effect upon the respectivereactions, 10 but are themselveseither not substantially affected ortransformed by the reactions and hence remain insoluble, or areoonvertedinto products which remain insolublein the reaction mixtures.

Consequently they can be easily -and readily removed from the reactionproduct comprising the converted cellulosic material: by, for example.simple filtration of a solution oftlie'lattera't'some stage in or afterits production. The cellulo'sic materials obtained aftersuch separationof the impurities brought into it from the reclaimed mattress stufiingusedas a source of cellulose will be entirely the equal in any and everyrespect of like products producedfrom a substanv by purification of, forexample, rawcotton linters.

Themethod in accordance with this invention forthe production'ofcellulosic'jmaterials from reclaimed mattress ,stufilng will accordingly'comprise a two-stage procedure. The first stage of procedure involvesthe purification of the reclaimed mattress stufilng by cookingwithjalkali under pressure for: the removal therefror'noi suchimpurities as are solubilized thereby. "This a1- kali or caustic cook isessentially the sameknown purification treatmentas is utilized injthepurification of cotton linters to produce a high alpha celluloseproduct. It may befollowed by bleaching treatment, just-as. is. the casewhen cotton I g I 40 The alkali cook serves both to remove impuris tiesandlto reduce the viscosity of thecellulose. The viscosity ofthe'cellulose must be reduced" to within a predetermined range, if thepurified product is to be used for certain purposes, as for example, themanufacture ofviscose,*and accordingly the alkali cook mus t'becontinued untilthe desired reduction is effected; I i i I Surprisingly,it has been found in accordance with this inventionthat the viscosity ofthe'cellulose present in reclaimed mattressstumng'tis much lower thanthe viscosity of cellulose present in raw cotton. Thus-cellulose from.mclaimed mattress stufll'ng has a viscosity, after extraction with etherfor the removal iofiats,

etc., of the order oi. 200-500 seconds as measured by the oflicialAmerican Chemical Society method, while cellulose from native cotton, ascotton linters, has a viscosity, after extraction with ether, of theorder of 5000 seconds on the same scale as calculated by conversion 01!the direct measurements made in more dilute solution. (Directmeasurement of such viscosities by the A. C. S. method is not possible.)

Accordingly, ,while the concentrations of alkali and pressures used inthe purification of reclaimed mattress stock will be essentially thesame as those employed for the purification or cotton linters, the timeof treatment may be much less since a much smaller reduction inviscosity of the cellulose need be effected. This results in economiesin steam consumption and in time of treatment.

The washing and bleaching treatmentsjollowing the caustic cook will bethe same as those used in the purification of cotton linters.

The second stage of procedure in the method in accordance with thisinvention involves the conversion of the partially purified mattressstock containing impurities not removed in the first stage into aregenerated cellulose, cellulose esters, cellulose ethers, etc. Thepartially purified mattress stock will be converted into these productsby treatment by any of the known methods for the production of thesematerials from pure cellulose. Thus the partially purified mattressstock may be treated with ccpperammonium hydroxide or with alkali andcarbon disulfide for the production of regenerated cellulose, withnitric and sulfuric acids for the production of cellulose nitrate, withacetic anhydride and. its homologues for the production of celluloseacetate and homologous esters, and with alkali and benzyl or ethylchloride for the production of cellulose ethers. The only importantvariation which may be introduced in the respective reactions as appliedto pure cellulose as a raw material will be to effect separation of theimpuritiespresent, for example, by filtration, at some stage in thereaction when the cellulosic material is in solution. If desired, theseparation may be effected after completion of the reaction bydissolving the cellulosic material containing the impurities in asolvent and filtering the solution. In all other respects the variousreactions can be conducted in the same manner as if pure cellulose wereused as the raw material instead of the partially purified mattressstock.

The various reactions involving the method in accordance with thisinvention specifically set forth in the following examples will serve toli lustrate its wide applicability.

Example I Preparation of regenerated cellulose cuprammonlum processsolution of sodium hypochlorite containing 0.025% available chlorine.The stock is their washed again and after souring with 0.025%

sulphuric acid it may, if desired, be again bleached at room temperatureto obtain a better color. At this stage the stock will have a chemicalanalysis substantially as follows:

Viscosity (A. c. s.) seconds 5 Soda soluble 3.00 per cent Ash. 0.20 percent Alpha, cellulose 98.5 per cent Ether extract 0.2 per cent 10 Theabove chemical analysis might indicate that the product is suitable formost chemical purposes but it will be noted by inspection that particlesof wood, trash, straw, jute and hemp still remain. These can be readilyshown up by 15 proper staining with a dye, as safranine or rutheniumred, or by solution of the cellulose in 72% sulphuric acid. The stockwould accordingly he considered as only partially purified and unlit foruse in chemical processes.

However, this partially purified steels may be directly converted intoregenerated cellulose, cellulose esters, cellulose ethers, etc. bymethod in accordance with this invention eithimmediately following thepurification procedure referred to above or at any later period.

Thus, such partially purified. cellulose while containing, say, 40-60%water may be dissolved by churning in any desirable concentration of acopper solution, such as a basic r suiplt a; solution or a copperhydroxideshia selution. "Ihe resulting solution, which still. con

reclaimed mattress stock, is

through, for example, finely wove for the removal of these impurities,la. lution of cellulose fully the e tained from completely 3: andsuitable for such purp threads of regenerated or fore, be used for allsuch manner the solutions cellulose now find employment.

Example 1.?

Preparation of cellulose acetate example, a for one hour, we" rebleashewith a tall leach as be the The prorluc. th s point will have ti foucwmganalysis:

Viscosity it.) M i si -ands Alpha cellulose M p a; Soda solu 3:

sure of cool sira'ole up by or in "l sulphuric ii llfi,

previously mentioned. The dr tiaily purified or during the 'processotripening or hydrolysis '01 the dissolved cellulose acetate, the'acetatesolution may be filtered to remove the insoluble impurities after whichthe cellulose acetate may be precipitated from solution in the'u'sualmanneri-yj I I into a tumbler barrel orx'anthatordntowhich It isalsopossibleto precipitate the cellulose acetate weenie: with theinsoluble impurities byordinary methods and after drying, dissolvetheacetate ina solvent, jas acetone, and filter or centriiulethe solutionto remove the'insoluble impurities. The resulting acetone solutionmay-be cast into films or spun into threads. The cellulose acetateproduced is in" all fully the cellulose. "sen pl e m equivalentot theproduct made-iron completely rre drdtt nw regenerated cellulose 'bu the9th A case process I a krams oi reclainiedmattress stock are im- 05me'rsed in approximately 4 liters 01 a aqu'e-. oussolution oi-NaOH- Asmall quantity of a detergent; as for example; a soap or iatty acid(about agrams) may be added in orderto secure 'a better scouring action,.The stock and'solution are charged into aEdizester and brought by in-.-iection of" steam toa. pressure 01,80 lbs.- persquare inch} whichismaintainedior 3 to 4 hours.

The pressure is thenreleased andthe'stock, well washed with'fwater toremove theexcess h and the dissolved impurities.

The stock is then bleachedwith sodium hypoe chiorite, substantiallyasgdescribed in the above example. It is then beaten in ahollanderbeater and pumped through a Jordan engine to reduce the "fiberlengthand to eliminate knots in the ,etock, The foreign material notremovedin the digestion and bleaching; suchas woody material andtrash-will becomminuted but will; nevertheless, remain'in thejstock, 1After the is ad- Q Justedto the propel-consistency it-mayhelead i out.on a Iburdrinier .wire or screen, as is cusmm in paper makinsifland finally dried in a 'sheeted condition; At this 'step' the ,stoc k will haveachemical substantially as follows: 7

5 The aboveianalysislindicates that the-product ,wculdbe suitable forusein making viscose-but,

inspection by staininy or solution in sulphurica'cid will show that itstill contains finely comminuted non-alphacellulose impurities. However,despite lowingjmanner.

100 mm 01' the which may bein sheetediorm, reduced to the.proper else,are steeped in 2%; litersoi an 18%- aqueous ,eodium hydroxidesolution at183C. After steepin. which eilfectsmercerisation and iormationot alkalicellulose, the excess caustic solution is-ex pressed by useoi ahydraulicpress to such apoint that the stock'and retained causticsolution weigh" 300 'I'he alkali cellulose er cellulose and '15.8%"oiNaOH. i

'l'healkjali'celluloseislthen I made in. this manner will contain"about1'.5%

above it would bedesirable to aae at 18 90. for

' about 96 hours,

= 'Aiter the alkali ceuuieee is introduced 323 grams r carbon disulphideerezmtredueedt 1o The massischurnedior'aboutz hours eta tem-" perature'of 25 C.- The cellulose xanthate. which n am n d w th s uble; unx n s ed-I purities; is dissolved in an alkali solution ofsuiflclentconcentration to give a viscose isolution is Y containingabout 7% of cellulose T and 6% NaOH;

solution,1ikefany.other viscose, must then be-ripenedat about 18 to2091C, for a periodoi" from 48 to 72 hours in orderto the correct.degree of coagulability; as measurcdg io by its salt index." During thisperiod 01 ripening the solution maybe separated from the w impuritiespresent. isreadily accomplished bylflltration oi. the solution. jSince'the solution is less viscous that described in Example 1, 2s andsince iine cambric or cotton batting willfnot be affected by thesolution; such materials may be used as flltering mediums It may bedesirable to eflect separationroithe impurities by super-cen- Itriiuaa'tio'n, since the finely comminutedparticles of unxanthatedimpurities cannot readily be removed-by filtration. it

i at the I desired ,coag ulability tne viscose s ldtion should haveavisc'osity at 18 C. otBSpoises,

which is considered satisfactory for extrusion," aszinsheeting orspinning, whichmay' be performed injthe usual manner; The regeneratedcellulose soproducediis fully the equal oithat madei'rom completelypurified cotton linters.

.500 of mattress stock-are treated with 3% liters'oi a-12-.51% -aqueoussolu- 44 honor NaOH. "Ihe.mixture is'chargedinto a digesterand raised toa steam pressure of' about '70,.;lbs.. square inch which ismaintainediww from-8 to'i'hoursu: The pressure is then released andthe material'washed and-bleachednubstan- 59 tiaily as describedin the previousexamples. after which it is dried-ton moisturecontent ct 1% or i iessrAt thisstace the; productiwll ere * Tlfls predates. be nitrated with,stem able nitratinz acid. but low temperature;

time nitrations, toiow nitro en contents 'arc preferable; in,.order tominimise the danzers es ue to any decomposition oi theimpuritiessubsequeht'to nitration. 'lhumdl'arams oithis'dry materialmay-be nitrated 'at'fa temperatiu'e of about 88C. for a periodic! lominutes' with f about)?! grams of mixed acid ctmsistii'is el- 79 d mtricacid. 5 p u l' gldd' and 19% watch An li'fignitrosen type ofcellulose-isobtained.-.-I a .6 v t nitration the v product iscentrifuged-- in order to removethe'excess acid. yashed in weer. v

and finally boiled in 0.1% sulphuric acid in order to effectstabilization, after which it may be boiled in neutral water. Theproduct may be dried by heat or de-hydrated with alcohol in the cusbefound that substantially all of the impurities brought in from, theoriginal mattress stock and not removed during the preliminarypurification remain in the heel of the stock left in the press. Afterthis hydraulic filtration, the extruded nitrocellulose plastic, withexcess solvent, may be worked up into such articles as sheets, rods,tubes,

etc., which are substantially equal to those made from nitrocellulosemade from a fully purified cellulose.

The procedure is not limited to the production of low nitrogen products,and higher nitrogen products can also be made, attended, however, bygreater risks of decomposition and fire.

Example V Preparation of nitrocellulose Thus, a 12% nitrogen type ofnitrocellulose may be produced by lowering the water content of the acidin the above example to about 17% with a corresponding increase in thestrength of the acids. The nitrating temperature may also be increasedup to about 45 or 50 C. with the production of a very low viscositynitrocellulose. This material, after stabilization, may be dissolved ina suitable solvent, such'as, for example, acetone, etc., to form arelatively thin'solution which can be easily filtered to removeimpurities brought in from the mattress stock. The nitrocellulosesoproduced may be cast in films or used in any way in whichnitrocellulose produced from completely purified cotton linters, withwhich it is fully comparable, may be used.

The method in accordance with this invention will be seen to be directedbroadly to the production of cellulosic materials, as for example,regenerated cellulose, cellulose esters, cellulose ethers, etc. fromwaste cellulose products, as reclaimed mattress stuffing or stock, etc.Accordingly it is to be understood that it is not limited to thespecific procedures and processes set forth herein by way of exampleonly, but is only limited by the claims hereinafter set forth.

What I claimand desire to protect by Letters Patent is:

1. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufiing to treatment adapted to remove aportion of the non-alpha-cellulose constituents thereof, treating thepartially purifiedmaterial so produced to form a solution ofalpha-cellulosic material in which non-alpha-cellulosic material isinsoluble, separating the insoluble non-alphacellulosic materialsderived from said partially purified mattress stufling from saidsolution, and recovering a cellulosic'material from said solution. l

2. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufilng to treatment adapted to remove aportion of the non-alpha-cellulose constituents thereof, dissolving thealpha-cellulose out of the partialb purified material so produced,separating the insoluble ,non-alpha-cellulosic materials derived fromsaid partially purified mattress stuffing from said solution, andrecovering regenerated cellulose from said solution.

3. The method of producing a cellulosic mate- 5 rial whichincludessubjecting reclaimed mattress stuiiing to treatment adapted to remove aportion of the non-alpha-cellulose constituents thereof, treating thepartially purified material so, produced toefiect formation of a soluble1o chemically substituted cellulose from the alphacellulose portionthereof, dissolving said chemically substituted cellulose in asolvent'therefor which is a non-solvent for the non-alpha-cellulosicmaterials derivedfrom said partially puri- 15 fled mattress stufiing,separating said non-alphacellulosic, materials from said solution, andrecovering a chemically substituted cellulose from said solution.

4. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufiing to treatment adapted to remove aportion of the non-alpha-cellulose constituents thereof, treating thepartially purified material so produced to effect formation of a solublecellulose 25 ester from the alpha-cellulose portion thereof, dissolvingsaid cellulose ester in a solvent therefor which is a non-solvent forthe non-alphacellulosic materials derived from said partially purifiedmattress stuffing, separating said mm 30 alpha-cellulosic materials fromsaid solution, and recovering a cellulose ester from said solution.

5. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufiing to treatment adapted to remove aportion 35 of the alpha-celluloseconstituents thereof, treating thepartially purified material so produced to effect formation of cellulosenitrate from the alpha-cellulose portion thereof, dissolving saidcellulose nitrate in a solvent therefor which is a 40 non-solvent forthe non-alpha-cellulosic materials derived from said partially purifiedmattress stuffing, separating said non-alpha-cellulosic materials fromsaid solution, and recovering cellulose nitrate from said solution. 45

6. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufling to treatment adapted to remove aportion of the alpha-cellulose constituents thereof, treating thepartially purified material so produced to 50 eflect formation ofcellulose xanthate from the alpha-cellulose portion thereof, dissolvingsaid cellulose xanthate in a solvent therefor which is a non-solvent forthe non-alpha-cellulosic materials derived from said partially purifiedmattress stufiing, separating said non-alpha-cellulosic materials fromsaid solution, and recovering regenerated cellulose from said solution.

7. The method of producing a cellulosic material which includessubjecting reclaimed mattress stufiing to treatment adapted to remove aportion of the non-alpha-cellulose constituents thereof, dissolving thealpha-cellulose out of the partially purified material so produced witha basic cupric' solution, separating the insoluble 5non-alpha-cellulosic materials derived from said partially purifiedmattress stufling from said solution, and recovering regeneratedcellulose from said solution.

8. The method of producing a cellulosic material which includessubjecting reclaimed mattress stuiiing to treatment with dilute aqueousalkali solution at an elevated temperature to effect removal of thealkali soluble non-alphacellulose constituents thereof, treating thepar- I tially purified materialfso produced toiorm a' 1 solution ofaipha cellulosic material in which non-alpha-cellulosicmaterialisinsoluble; separatingthe insoluble I I rials derived from saidpartially purified e and recovering a .non-alpha-cellulosic mate--stumngf' from said solution,

cellulosic material from said solutions, 1 t

3 9; The method oi. producing a cellulo'sic lution,"andrecoveringachemically substituted 1- '85 which includes s biecting reclaimedmattress stufllng', to treatment with dilute-aqueous alkalisolutionat'i-an f=,e1evatedtemperatureto eirectremoval or'the alkali"solublenon-alpha cellulose constituents. gthereof; diS OlVIng thealpha-cellulose out time, partiall Purified, ma- I produced,separatingthe insoluble non.- jliplia-celluloslc materials derivedjfrom" saidpartiallypurifled I I lution, andrecovering regenerated celluloseirom.

mattress stufilng from; said so-' said "solution. 10; Themethod tressstumng totreatnrent with dilute aqueous alkali solution I I I I seflect' removal .of the alkali soluble non-alpha:

cellulose lose from the alpha cllulose portion thereof,

' dissolving said ,chemicallyf substituted cellulose .in a solventtherefor which is a non-solvent vfor the non-alpha-cellulosicimaterialsderived from said partially purified mattress stuffing, separatcellulosefrom said solution,

" lllThe method of producing terial gwhicl-r: includessubjectingreclaimed mat-:1

I ,:alka1 solution" at an constituents thereof,

efle'ct removal or 'theialkallisoluble mation o t-a solublecellulosee'ster'irom the alphacelluloseportionthereof, dissolving saidcellulose ester in a solvent therefor which is a non solvent for the Inon alpha-cellulosic materials derived -irom said partially purifiedmattress stufling, sept arating' said non-alpha-cellulosic materialsfrom said solution," and recovering a celluloseester fromsaid solution;

. 12. The method oi" producing a cellulosicfmate rialwhichlincludessubjecting reclaimed mattress I stumng to treatment, with dilute aqueousalkali-I solutionvat an elevated temperature toeiIec tQr'emoval oi. thealkali soluble non-alpha cellulose I I treatingthe partially'lpwh fledmaterial soproduced toefiect' formation 1o! 1- cellulose nitrate fromvthe alpha-cellulose portion thereof, dissolving said cellulose nitratein a solvent therefor which is a non-solventronthenonof producing acellulosic ma-- terialfwlhich includes subjecting reclaimed mat at anelevated, temperature to constituent's 'thereof; treating the par-- Imaterial sa-produced to effect forp motion of a soluble chemicallysubstituted icelluellitd;,temperature fto oman I-gceiluloseiconstituents thereotistreating the partiallypuriflulmaterial sosproduced to eiiect forellulosic materials derived from saidpartially purified mattress stuifing, 'separa'tingsaid''non-alphaj-cellulosic materials from said. solutiori,;

and recovering cellulose nitrateqlrom said solution. Y

remova 0: the alkali soluble 1 noh-alpha constituents thereoi treatingthe parti 13.1"Ihe method 0! producing acellulcsicjma- [terial whichlincludes subjectingreclaimedlmattressstufling to treatmentwithdiluteaqueous alkali solution atv an elevated temperatureto effect?dellulose puricellulose Xanthatefrom'the alpha-cel ulose p'ortion.thereoLdissolvihg said cellulose "nthate in asolvent therefor whichis anon-solvent'ior the partially purified mattress-" stufling, separatingfled material so-produced toefiect fInation of non-alpha-cellulosicmaterials} derived from said saidr-non-alpha-cellulosic materials; 1mmsaid 1 from said solution;

14;:The ethod of producing a cellulosic material which includes subjectingreclaimed mattress stumng to treatment with" dilute aqueous alkalisolution at anelevated temperature toeflect relulose'out or thepartially purified material so produced-with a basic eupric solution;separating j'theinsolublef min-alpha;-cellulosic materials de-'solution; r and" recovering regenerated; cellulose l I v r moval ofthealk ali soluble non-alpha-cellulose 2 f constituents thereof;dissolving the alpha-och rived Iromsaid partially purified mattressstuff- 30 ing from said solution, and recovering regenerated cellulosefrom. said solution.

.ri al which includes-subjecting reclaimed niattress stufflng totreatment "with dilute aqueous" alkali ,15, 'Themethod of producing acellulosi'c mate-' solutionat anflelevated temperatureto e'flect re- Imovali of jthe alkali soluble; non-alpha cellulose constituentsthereotbleachingthe treated mate- -rial,',treating the partiallypurified material so roduced to torm a 's'olutionfot alpha-'cellulosic}vmaterial injivvhich non-alpha cellulosic material is insoluble,separating the insoluble non-alpha 1' cellulosic materialsflderlved fromsaid partially purified mattress stufling 'from's'aid'solution, and

. ,recoveringacellulosicmaterial from saidsolution. 16L Aucellulosi'cmater'ial suitable lorchemical tivesi therefrom comprising I reclaimed Imattress stufling that has been partially purified bychemical dyeand'unremovable from: said" material by cellulose present,1saidnon-alpha-cellulosic" im purities being substantially vwithout harmfuleffect on reactions Iorithe production of cellulose in solventstoralpha-cellulose, I I

i WYLYM.BILIJNG.'

1 treatment tor the production or cellulosederlvatreatment but stillcontains non-alpha-cellulosic. I impurities detectable by' stainingwitha suitable I r chemical methods that are "non-deleterious to'the Iderivatives from said material and'beinginsoluble

